The biochemical composition of a cell is a complex mix of biological molecules including, but not limited to, proteins, nucleic acids, lipids, and carbohydrates. The composition and interaction of the biological molecules determines the metabolic state of a cell. The metabolic state of the cell will dictate the type of cell and its function (i.e., red blood cell, epithelial cell, etc.). Tissue is generally understood to mean a group of cells that work together to perform a function. Raman spectroscopic techniques provide information about the biological molecules contained in cells and tissues and therefore provide information about the metabolic state. As the cell's or tissue's metabolic state changes from the normal state to a diseased state, Raman spectroscopic techniques can provide information to indicate the metabolic change and therefore serve to diagnose and predict the outcome of a disease. Cancer is a prevalent disease, so physicians are very concerned with being able to accurately diagnose cancer and to determine the best course of treatment.
The vast majority of cancer cases are pathologically diagnosed tissue from a biopsy specimen. An experienced pathologist can provide diagnostic information used to make management decisions for the treatment of the cancer. In the case of prostate cancer, the tissue sample is given a Gleason score based on the appearance of the prepared, stained tissue section which is a measure of how far from normal the tissue appears. In general, the higher the Gleason score, the more aggressive the cancer. However, there are cases where patients with a relatively low Gleason score progress to metastatic disease, and there are cases where patients with a relatively high Gleason score have a benign course. The current methods of Gleason scoring are not necessarily predictive of a clinical outcome.
Raman spectroscopy may be explored for detection of various types of cancers. Because Raman spectroscopy is based on irradiation of a sample and detection of scattered radiation, it can be employed non-invasively to analyze biological samples in situ. Thus, little or no sample preparation is required. Raman spectroscopy techniques can be readily performed in aqueous environments because water exhibits very little, but predictable, Raman scattering. It is particularly amenable to in vivo measurements as the powers and excitation wavelengths used are non-destructive to the tissue and have a relatively large penetration depth. Therefore, it is desirable to devise methodologies that use Raman spectroscopy techniques to differentiate various cell types (e.g., normal, malignant, benign, etc.), to classify biological samples under investigation (e.g., a normal tissue, a diseased tissue, etc.), and to also predict clinical outcome (e.g., progressive or non-progressive state of cancer, etc.) of a diseased cell or tissue.